In a medium bowl, add the tomatoes, cucumbers, cilantro, and onions and toss.
In a measuring cup or in a bowl, stir together the olive oil, red wine vinegar, garlic powder, Mexican oregano, crushed red peppers, salt, and pepper.
Pour the vinaigrette over the cucumbers, tomatoes, cilantro, and onions, and let marinate. Allow this salad to sit for as long as an hour for the flavors to blend.